DESCRIPTION: (Applicant's Description) Pathological neovascularization of the retina can cause vision loss and blindness. Inhibitors of angiogenesis present in normal eyes may be therapeutically useful to suppress abnormal blood vessel proliferation in diseased eyes. We have isolated a novel acetyltransferase, tubedown-1 (tbdn- 1), with protein-protein interaction and DNA-binding motifs which is expressed exclusively in the corneal endothelium and in the limbic and retinal vascular endothelia in the normal eye. Tbdn-1 is absent or downregulated in blood vessels undergoing neovascularization in diseased and injured eyes. Inhibition of tbdn-1 stimulates angiogenesis in embryonic vascular endothelial cells in vitro, suggesting that tbdn-1 may be an angiogenesis inhibitor. These results together lead us to hypothesize that tbdn-1 may serve to inhibit angiogenesis in the normal eye. The goal of this project is to explore the functional role and potential utility of tbdn-1 as an inhibitor of retinal angiogenesis. Specific Aim 1: The functional role of tbdn-1 in retinal endothelial cells will be characterized. Tbdn-1 expression will be further studied in a model of retinopathy of prematurity and in specimens of proliferative diabetic retinopathy and macular degeneration. The effects of altering tbdn-1 expression levels on the angiogenic differentiation potential of retinal endothelial cells will be studied in vitro by overexpressing antisense and sense tbdn-1 cDNA in RF/6A rhesus retinal endothelial cell lines. Immortalized human retinal endothelial cell lines (HRVE) will be established using the human papilloma virus E7 protein, the human telomerase reverse transcriptase subunit (hTERT) or SV40 Large T antigen to provide in vitro model systems to further study and validate the functional role of tbdn-1 in human retinal vascular endothelium. Specific Aim 2: Functional activities of tbdn-1 in the context of retinal endothelial cells will be defined. This aim will explore the hypotheses that tbdn-1 inhibits angiogenesis in retinal endothelium through its acetylation activity, protein-protein interactions, DNA-binding activity or a combination of these. These properties will be examined in the specific context of angiogenesis of RF/6A cells or HRVE cells using an anti-tbdn-1 antibody and tbdn-l-GST fusion protein. The findings of this project could indicate tbdn-1 as a potentially useful therapeutic target for treating eye diseases involving retinal neovascularization.